In the modern world, telephone transactions involving extensions of credit, payment of bills, fund transfers and the providing of other types of services are commonplace. Generally, such services are provided in response to a user dialing the telephone number of a service and by then entering identification information and/or credit card information using standard "touch tones", i.e., dual tone multi-frequency signals ("DTMF tones"), to represent the identification information being entered and transmitted. Normally, such touch tone signals are produced using a standard telephone keypad input device.
Touch tones are generated using a dual tone multi-frequency (DTMF) encoding technique, as opposed to a frequency shift key (FSK) encoding, which is frequently used for data transmission purposes. In accordance with the DTMF technique used to generate touch tone signals, tone signals are produced by generating two tones such that one tone is selected from a high frequency band group and the other tone is selected from a low frequency band group. In standard telephone systems, the high frequency band group includes four high frequencies (1209, 1336, 1477, and 1633 Hz) while the low band frequency group includes four low frequencies (697, 770, 852 and 941 Hz). Each of the high and low frequencies is referred to as a fundamental frequency.
Each one of the low frequencies corresponds to one of the four rows of keys on a standard extended telephone keypad while each one of the four high frequencies corresponds to one of the four columns of keys on standard extended telephone keypads. Accordingly, low frequency tones represent row tones and high frequency tones represent column tones. It should be noted that extended and non-extended keypads differ in that extended keypads include the additional fourth column of keys not found on non-extended standard keypads such as those commonly used with public telephones and household telephones, although these additional tones are found in most modem hardware/software systems.
Each different telephone key is represented by a signal including a unique combination of one tone from the high band and one from the low band. Sixteen different signal states may be represented by this encoding technique with one signal state corresponding to each one of the sixteen keys that can be found on a standard telephone keypad. Referring now to FIG. 8A, there is illustrated a chart which lists the 16 different numbers/symbols that are represented by the 16 different signal states and the Hi-tone and Lo-tone frequency associated with each of the 16 different signal states.
A received DTMF tone signal is determined, in telephone switching and DTMF tone signal detection devices, as having a valid signal state if five conditions are met. The first of these is that the tone signal contain exactly one valid tone, and only one valid tone, from each of the low and high band frequency groups, i.e., the signal must contain only one valid Hi-tone and one valid Lo-tone frequency. The second condition is that the low and high tones are present for a predetermined minimum time duration, i.e., at least 35-40 milliseconds. Third, the difference in power (level), commonly referred to as "twist", between the low and the high tone must fall within a predetermined range, i.e., the Hi-band tone signal power level can not be more than 4 dBm greater or 8 dBm less than the Lo-band tone signal power level, where dBm is a logarithmic measure of power with respect to a reference power of 1 milliwatt. Fourth, the amplitude level of each tone signal in the tone pair must be in the range of 0 to -25 dBm. Fifth, consecutive tone-pairs must be separated by a period of silence for at least 35-40 milliseconds.
Thus, if too many or too few tones are detected the detection criteria will not be met and a valid signal state will not be indicated. When a valid signal state does occur, the particular combination of low and high tones is decoded to produce an indication of the corresponding key or signal state that was responsible for the generation of the DTMF tone signal. It is this key or signal state information that represents, e.g., one of the numerical digits comprising a telephone or credit card number.
Placing a voice call, using a calling card number or other credit card number, is exemplary of one of the most common types of telephone credit transactions involving the use of DTMF tones.
Referring now to FIG. 1, there is illustrated a flow chart illustrating a standard telephone call transaction involving the use of a credit card for billing purposes. As illustrated, the standard telephone call transaction comprises the first step of making a decision to place a credit card call 1001 followed by the actual step of dialing 1002. As part of the dialing step 1002 a user enters, using, e.g., the telephone keypad, an access code identifying the desired long distance telephone carrier, and a destination number, i.e., the telephone number of the party being called. Both the access code and telephone number are represented as DTMF tones, i.e., touch tones, generated by the telephone in response to the keypad input.
The telephone system, e.g., the local switching office to which the telephone is linked, connects the caller to the appropriate long distance carrier represented by the access code input by the user. The long distance carrier then generates an audible signal/message indicating to the caller that it is ready to receive billing information as indicated in step 1003.
In response to the audible signal/message generated by the long distance carrier, the caller then inputs, e.g., using the telephone keypad, a credit card number as illustrated in step 1004. In response to receiving DTMF tones representing the credit card number, generated by the telephone, the long distance carrier checks the credit card number for validity as illustrated in step 1006. If the credit card number is determined to be valid, the call is placed as illustrated in step 1008. However, if the credit card number is determined to be invalid, the call is rejected and the telephone connection is disconnected as illustrated in step 1010.
The standard procedure for placing a call using a credit card has several drawbacks. For example, requiring a caller to manually input through the telephone keypad a carrier access number, a destination number, and a credit card number introduces into the calling procedure ample opportunity for a user to accidentally input an incorrect number for any one of the required values, which can exceed, e.g., 35 required inputs--more if the call is placed to or from a foreign country.
It is generally understood that the likelihood of entry errors increases in proportion to the number of digits to be entered. Such an error normally results in the call being rejected by the telephone carrier, requiring the caller to repeat the entire calling procedure from the point of connection to the long distance carrier. Generally, the long distance carrier pays fees to the company which owns the originating local switching office of the caller from the moment of connection, and is unable to start billing for the ultimate connection until the moment of connection. In such a case, each entry error is an increase in the unbillable time that a long distance carrier must absorb without any offsetting revenue.
Generally, the requirement that a caller manually input a large series of numbers to place a call leads to a higher error rate during call placement than results when the caller has to input fewer numbers, e.g., when calls are placed without the use of credit cards. In addition, requiring a caller to manually input a calling card number discourages some callers from using a credit card to place a call because of the additional time and frequent input errors associated with the initiation of a call as compared to calls placed without using credit cards.
In addition to error problems associated with the manual input of credit card number information, security problems are also associated with the manual input of credit card data into a telephone using a standard keypad. For example, a person viewing the initiation of a telephone transaction can record the credit card number input to the telephone keypad and then later use the calling card number to place unauthorized calls.
Portable electronic information cards and auto-dialers that are capable of being acoustically coupled to telephone systems to perform dialing functions are well known in the art.
Such known devices which generate a series of DTMF tones representing the numbers which must be input to initiate a call, have reduced or eliminated the need to input telephone number, carrier number, and credit card number information manually each time a call is placed.
Frequently, to enhance the versatility of such devices, they are made programmable with individual devices being programmed to store different telephone numbers, and/or calling card, credit card or personal identification numbers (PINs). While such programming is generally performed by electronically coupling such programmable devices to a programming unit, for example, as described in U.S. Pat. No. 4,882,750 to Henderson et al., it has been suggested that such devices should be designed to be capable of being programmed by acoustic signals received from a telephone. For example, PCT Patent Application Number 02837, now abandoned, suggests a portable electronic information card capable of being programmed in response to acoustic signals.
While known portable electronic information cards and auto-dialers that can be acoustically coupled to telephone systems facilitate telephone dialing and the supplying of billing information over the phone, the lack of a practical workable device which deals with past data transmission errors and security problems has inhibited widespread acceptance and use of such auto-dialer devices.
The introduction of errors into the data being sent to the telephone system, e.g., as the result of the use of an acoustic coupling, is one example of a data error problem that may prevent the telephone system from completing a call. As will be discussed in detail below, errors associated with the use of an acoustic coupling result from various factors affecting the acoustical transmission of DTMF tones. Such factors include variations between components used in present auto-dialers to generate the DTMF tones, temperature variations affecting battery voltages and the amplification levels applied to DTMF signals, speaker proximity to a telephone handset's microphone used to receive the acoustic DTMF tones, distortions introduced by the microphone receiving DTMF tones output by an auto-dialer, as well as, ambient noise levels. Errors may also be introduced from the lines that connect a caller to the ultimate telephone call destination as well as from other sources.
In addition to the error problems associated with the use of known auto-dialers, known devices for providing calling card and caller identification information acoustically to a telephone system present many security problems. For example, an unauthorized tape recording of a calling card number generated by the known systems, can easily be created by connecting an input cable to the telephone cable connected to a coin phone and then played back by an unauthorized user seeking to obtain access to the telephone system. Generally, the known calling card systems fail to provide a security method for preventing unauthorized users from gaining access to the telephone system via the use of such an unauthorized recording. Furthermore, known systems fail to prevent an unauthorized person from obtaining a calling card number and its related Personal Identification Number (PIN), both of which can be repeatedly used in their identical form for subsequent calls, through other methods, e.g., video-taping an authorized caller in a public place, going through the trash outside of large office facility, etc. Once known, calling card number and PIN data can be used to initiate multitudes of calls, often to foreign countries. The aggregate cost of the fraudulent use of unauthorized calling card calls in the United States is estimated to exceed $1 billion per year. While long distance carriers are now providing software analysis of many calls placed on their network to determine if there is a likelihood of unauthorized use, many such calls are paid by authorized customers who fail to notice the unauthorized calls on their bills.
Accordingly, there is a need to provide a secure device and method for storing and providing information regarding a user, and, more specifically, for providing such information locally or transmitting it remotely by, e.g., calling card, credit card, and user identification information either through or to a telephone system.
In addition to the reliability and security issues discussed above, there are also several convenience problems associated with known auto-dialer devices some of which are inherent in the standard credit card calling transaction illustrated in FIG. 1. These convenience problems include the need to generate and/or input separate telephone number and calling card identification information when attempting to place a credit card call. Furthermore, the procedures often used to initiate a calling card call often require that a user interlace carrier access codes (up to 20 digits) followed by the user's desired destination number (up to 17 digits) followed by an account/pin number array (usually at least 14 digits). These input sequences, which may expand in the future to accommodate greater call/user volumes are difficult sequences for a user to supply without input errors, and because of their complexity often result in users holding a publicly viewable card showing the account number and dialing sequences needed, creating security risks from unscrupulous users of calling card account and access data.
Additionally, because many countries have a distinct dialing sequence and numbering plan, carrier access codes are rarely identical from country to country, thereby increasing the difficulty that a traveler experiences when placing a calling card call.
Other convenience problems with the known devices relate to size and general ease of use issues. For example, known devices may be of such a size that it is inconvenient for a user to keep the device with them throughout the day. In addition, the size and shape of many of the known auto-dialers makes it difficult to properly align the auto-dialer with the microphone of a standard telephone handset making it somewhat difficult to use if accurate transmission of DTMF signals is to be achieved. Furthermore, the number of keys and the complexity of the controls frequently encountered on the known portable electronic information cards and auto-dialers have tended to inhibit the known devices from gaining widespread acceptance.
While the problems described above mainly refer to the problems and errors associated with the initiation of calling card calls, each of these problems may also affect access security and convenience in relation to any telephone based transaction (e.g. credit card purchases of over the phone, access to secure voice and data networks, etc.).